Current Resonance Power Supply Light-Load Voltage Stability
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Solution Overview
Problem
Conventional current resonance type power supply devices experience intermittent operation and output voltage instability under light-load conditions when attempting to increase efficiency by varying duty ratios, leading to excessive output voltage beyond constant voltage control ranges.
Innovation Solution
A current resonance type power supply device with a control circuit that alternately turns on and off switch elements, setting their duty ratio closer to 50% as the detected voltage increases, using capacitors, resistors, and operational amplifiers to stabilize output voltage under light-load conditions by adjusting the ON/OFF times of the switch elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the duty ratio is varied to increase efficiency under light-load conditions, then energy efficiency is improved, but output voltage stability deteriorates
Solution Approach 1:
The patent applies dynamics by making the duty ratio adjustable rather than fixed. The control circuit dynamically changes the duty ratio based on operating conditions, specifically using different duty ratios for different switching periods. This allows the system to optimize efficiency under light-load conditions while maintaining voltage stability through dynamic adaptation rather than static configuration.
Solution Approach 2:
The patent changes the parameter of duty ratio to resolve the contradiction. By varying the duty ratio between different switching periods (using first and second duty ratios), the system can operate at higher efficiency under light-load conditions while preventing output voltage from exceeding constant voltage control ranges. The control circuit monitors and adjusts this parameter to balance efficiency and stability.
2Loss of energy
If the duty ratio is increased to improve efficiency, then energy loss is reduced, but output voltage exceeds constant voltage control range
Solution Approach 1:
The patent uses periodic action by implementing different duty ratios for different switching periods. The control circuit alternates between a first duty ratio and a second duty ratio across multiple switching periods, allowing the system to achieve improved efficiency over time while maintaining average voltage within control ranges. This periodic variation prevents voltage excursions while capturing efficiency benefits.
Solution Approach 2:
The system dynamically adjusts the duty ratio parameter based on the detected operating state. When light-load conditions are detected, the control circuit modifies the duty ratio to improve efficiency while ensuring the output voltage remains within acceptable ranges. This dynamic control prevents voltage precision degradation while reducing energy loss.
3Loss of energy
If intermittent operation is performed to increase efficiency, then energy efficiency is improved, but output voltage control stability deteriorates
Solution Approach 1:
The patent ensures continuity of useful action by maintaining continuous switching operation rather than true intermittent operation. The control circuit continuously switches between different duty ratios, ensuring that power delivery remains continuous and stable. This approach improves efficiency through duty ratio modulation while maintaining voltage control reliability through continuous operation and active control.
Solution Approach 2:
The system employs feedback mechanisms where the control circuit detects the operating state and adjusts the duty ratio accordingly. This feedback loop ensures that efficiency improvements through duty ratio variation do not compromise voltage control reliability. The control circuit continuously monitors and adjusts parameters to maintain stable output voltage while achieving energy efficiency goals.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively stabilizes output voltage control under light-load conditions by adjusting the duty ratio of switch elements, reducing charging/discharging current and loss, and maintaining constant voltage accuracy.
Implementation Method 1
a series circuit of a resonance reactor Lr, a primary winding P of a transformer T and a current resonance capacitor C2 is connected across ends of the switch element Q2
Implementation Method 2
A secondary winding S1 and a secondary winding S2 of the transformer T are connected in series
Implementation Method 3
a full-wave rectifier circuit RC1 which rectifies an AC (alternating current) voltage
Implementation Method 4
a smoothing capacitor C3, and the other end of the smoothing capacitor C3 is connected to a junction of the one end of the secondary winding S1 and the one end of the secondary winding S2
Data Source
AI summary
Embodiments of the invention may include: a series circuit connected to a junction of a first switch element and a second switch element connected in series across ends of a DC power supply, and to one end of the DC power supply, and formed of a primary winding of a transformer and a capacitor; a rectifier/smoothing circuit configured to rectify and smooth a voltage generated in a secondary winding of the transformer thereby to extract a DC voltage; a control circuit configured to alternately turn on and off the first switch element and the second switch element; a voltage detector configured to detect a voltage of the DC power supply; and a duty controller configured to, under a light-load condition, set a duty ratio between the first switch element and the second switch element closer to 50% as a value of the voltage detected by the voltage detector becomes larger.